W = "W"
R = "R"

N = int(input())
C = list(input())
numR = C.count(R)
result = 0
for i in range(numR):
    if C[i] == W:
        result += 1
print(result) W = "W" W "W" R = "R" R "R" N = int(input()) N int(input()) int input() input C = list(input()) C list(input()) list input() input numR = C.count(R) numR C.count(R) C.count C count R result = 0 result 0 for i in range(numR):
    if C[i] == W:
        result += 1 i range(numR) range numR if C[i] == W:
        result += 1 C[i] == W C[i] C i W result += 1 result 1 print(result) print result C = list(input()) list(input()) C result = 0 0 result N = int(input()) int(input()) N W = "W" "W" W numR = C.count(R) C.count(R) numR R = "R" "R" R result += 1 1 result
W = "W"
R = "R"

N = int(input())
C = list(input())
numR = C.count(R)
result = 0
for i in range(numR):
    if C[i] == W:
        result += 1
print(result)
